Actigraphy‐based assessment of circadian rhythmicity and sleep in patients with Usher syndrome type 2a: A case–control study

This study aimed to improve our understanding of sleep problems as a comorbidity of hereditary deaf-blindness due to Usher syndrome type 2a. Fifteen patients with Usher syndrome type 2a with a conclusive genetic diagnosis and 15 unaffected controls participated in comprehensive sleep and activity assessments for 2 weeks, using the MotionWatch 8 actigraph and consensus sleep diary. Various sleep parameters including sleep opportunity window, sleep latency, sleep efficiency, and self-reported sleep quality were analysed. Non-parametric circadian rhythm analysis was performed to evaluate circadian rhythmicity. Additionally, regression analyses were conducted to study potential correlations between sleep parameters and patients' demographics and disease progression. Patients with Usher syndrome type 2a exhibited significantly longer sleep latency and lower self-reported sleep and rest quality compared with controls. Additionally, day-to-day variability of sleep efficiency and sleep latency were significantly higher in the patient population. Non-parametric circadian rhythm analysis revealed no significant differences in circadian rhythmicity. Regression analyses indicated that having Usher syndrome type 2a was a significant predictor of poor sleep outcomes. No clear correlations were found between the level of visual impairment and sleep parameters, suggesting that the negative effects of Usher syndrome type 2a on sleep manifest independently of the progressive visual impairment. These findings suggest that, while circadian sleep-wake rhythm remain intact, patients with Usher syndrome type 2a suffer from sleep disturbances that likely arise from factors beyond their progressive blindness. With sleep problems being a major risk factor for physical and mental health problems, we advocate that sleep problems should be recognized as a hallmark symptom of Usher syndrome type 2a, warranting in-depth research for potential targeted therapeutic interventions.